builtin/pull.c

   1 /*
   2  * Builtin "git pull"
   3  *
   4  * Based on git-pull.sh by Junio C Hamano
   5  *
   6  * Fetch one or more remote refs and merge it/them into the current HEAD.
   7  */
   8 #include "cache.h"
   9 #include "config.h"
  10 #include "builtin.h"
  11 #include "parse-options.h"
  12 #include "exec_cmd.h"
  13 #include "run-command.h"
  14 #include "sha1-array.h"
  15 #include "remote.h"
  16 #include "dir.h"
  17 #include "refs.h"
  18 #include "revision.h"
  19 #include "submodule.h"
  20 #include "submodule-config.h"
  21 #include "tempfile.h"
  22 #include "lockfile.h"
  23 #include "wt-status.h"
  24
  25 enum rebase_type {
  26         REBASE_INVALID = -1,
  27         REBASE_FALSE = 0,
  28         REBASE_TRUE,
  29         REBASE_PRESERVE,
  30         REBASE_INTERACTIVE
  31 };
  32
  33 /**
  34  * Parses the value of --rebase. If value is a false value, returns
  35  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  36  * "preserve", returns REBASE_PRESERVE. If value is a invalid value, dies with
  37  * a fatal error if fatal is true, otherwise returns REBASE_INVALID.
  38  */
  39 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  40                 int fatal)
  41 {
  42         int v = git_config_maybe_bool("pull.rebase", value);
  43
  44         if (!v)
  45                 return REBASE_FALSE;
  46         else if (v > 0)
  47                 return REBASE_TRUE;
  48         else if (!strcmp(value, "preserve"))
  49                 return REBASE_PRESERVE;
  50         else if (!strcmp(value, "interactive"))
  51                 return REBASE_INTERACTIVE;
  52
  53         if (fatal)
  54                 die(_("Invalid value for %s: %s"), key, value);
  55         else
  56                 error(_("Invalid value for %s: %s"), key, value);
  57
  58         return REBASE_INVALID;
  59 }
  60
  61 /**
  62  * Callback for --rebase, which parses arg with parse_config_rebase().
  63  */
  64 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  65 {
  66         enum rebase_type *value = opt->value;
  67
  68         if (arg)
  69                 *value = parse_config_rebase("--rebase", arg, 0);
  70         else
  71                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  72         return *value == REBASE_INVALID ? -1 : 0;
  73 }
  74
  75 static const char * const pull_usage[] = {
  76         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  77         NULL
  78 };
  79
  80 /* Shared options */
  81 static int opt_verbosity;
  82 static char *opt_progress;
  83 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
  84
  85 /* Options passed to git-merge or git-rebase */
  86 static enum rebase_type opt_rebase = -1;
  87 static char *opt_diffstat;
  88 static char *opt_log;
  89 static char *opt_squash;
  90 static char *opt_commit;
  91 static char *opt_edit;
  92 static char *opt_ff;
  93 static char *opt_verify_signatures;
  94 static int opt_autostash = -1;
  95 static int config_autostash;
  96 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
  97 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
  98 static char *opt_gpg_sign;
  99 static int opt_allow_unrelated_histories;
 100
 101 /* Options passed to git-fetch */
 102 static char *opt_all;
 103 static char *opt_append;
 104 static char *opt_upload_pack;
 105 static int opt_force;
 106 static char *opt_tags;
 107 static char *opt_prune;
 108 static char *max_children;
 109 static int opt_dry_run;
 110 static char *opt_keep;
 111 static char *opt_depth;
 112 static char *opt_unshallow;
 113 static char *opt_update_shallow;
 114 static char *opt_refmap;
 115
 116 static struct option pull_options[] = {
 117         /* Shared options */
 118         OPT__VERBOSITY(&opt_verbosity),
 119         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 120                 N_("force progress reporting"),
 121                 PARSE_OPT_NOARG),
 122         { OPTION_CALLBACK, 0, "recurse-submodules",
 123                    &recurse_submodules, N_("on-demand"),
 124                    N_("control for recursive fetching of submodules"),
 125                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules },
 126
 127         /* Options passed to git-merge or git-rebase */
 128         OPT_GROUP(N_("Options related to merging")),
 129         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 130           "false|true|preserve|interactive",
 131           N_("incorporate changes by rebasing rather than merging"),
 132           PARSE_OPT_OPTARG, parse_opt_rebase },
 133         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 134                 N_("do not show a diffstat at the end of the merge"),
 135                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 136         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 137                 N_("show a diffstat at the end of the merge"),
 138                 PARSE_OPT_NOARG),
 139         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 140                 N_("(synonym to --stat)"),
 141                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 142         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 143                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 144                 PARSE_OPT_OPTARG),
 145         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 146                 N_("create a single commit instead of doing a merge"),
 147                 PARSE_OPT_NOARG),
 148         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 149                 N_("perform a commit if the merge succeeds (default)"),
 150                 PARSE_OPT_NOARG),
 151         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 152                 N_("edit message before committing"),
 153                 PARSE_OPT_NOARG),
 154         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 155                 N_("allow fast-forward"),
 156                 PARSE_OPT_NOARG),
 157         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 158                 N_("abort if fast-forward is not possible"),
 159                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 160         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 161                 N_("verify that the named commit has a valid GPG signature"),
 162                 PARSE_OPT_NOARG),
 163         OPT_BOOL(0, "autostash", &opt_autostash,
 164                 N_("automatically stash/stash pop before and after rebase")),
 165         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 166                 N_("merge strategy to use"),
 167                 0),
 168         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 169                 N_("option=value"),
 170                 N_("option for selected merge strategy"),
 171                 0),
 172         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 173                 N_("GPG sign commit"),
 174                 PARSE_OPT_OPTARG),
 175         OPT_SET_INT(0, "allow-unrelated-histories",
 176                     &opt_allow_unrelated_histories,
 177                     N_("allow merging unrelated histories"), 1),
 178
 179         /* Options passed to git-fetch */
 180         OPT_GROUP(N_("Options related to fetching")),
 181         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 182                 N_("fetch from all remotes"),
 183                 PARSE_OPT_NOARG),
 184         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 185                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 186                 PARSE_OPT_NOARG),
 187         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 188                 N_("path to upload pack on remote end"),
 189                 0),
 190         OPT__FORCE(&opt_force, N_("force overwrite of local branch")),
 191         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 192                 N_("fetch all tags and associated objects"),
 193                 PARSE_OPT_NOARG),
 194         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 195                 N_("prune remote-tracking branches no longer on remote"),
 196                 PARSE_OPT_NOARG),
 197         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 198                 N_("number of submodules pulled in parallel"),
 199                 PARSE_OPT_OPTARG),
 200         OPT_BOOL(0, "dry-run", &opt_dry_run,
 201                 N_("dry run")),
 202         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 203                 N_("keep downloaded pack"),
 204                 PARSE_OPT_NOARG),
 205         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 206                 N_("deepen history of shallow clone"),
 207                 0),
 208         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 209                 N_("convert to a complete repository"),
 210                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 211         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 212                 N_("accept refs that update .git/shallow"),
 213                 PARSE_OPT_NOARG),
 214         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 215                 N_("specify fetch refmap"),
 216                 PARSE_OPT_NONEG),
 217
 218         OPT_END()
 219 };
 220
 221 /**
 222  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 223  */
 224 static void argv_push_verbosity(struct argv_array *arr)
 225 {
 226         int verbosity;
 227
 228         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 229                 argv_array_push(arr, "-v");
 230
 231         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 232                 argv_array_push(arr, "-q");
 233 }
 234
 235 /**
 236  * Pushes "-f" switches into arr to match the opt_force level.
 237  */
 238 static void argv_push_force(struct argv_array *arr)
 239 {
 240         int force = opt_force;
 241         while (force-- > 0)
 242                 argv_array_push(arr, "-f");
 243 }
 244
 245 /**
 246  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 247  */
 248 static void set_reflog_message(int argc, const char **argv)
 249 {
 250         int i;
 251         struct strbuf msg = STRBUF_INIT;
 252
 253         for (i = 0; i < argc; i++) {
 254                 if (i)
 255                         strbuf_addch(&msg, ' ');
 256                 strbuf_addstr(&msg, argv[i]);
 257         }
 258
 259         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 260
 261         strbuf_release(&msg);
 262 }
 263
 264 /**
 265  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 266  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 267  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 268  * error.
 269  */
 270 static const char *config_get_ff(void)
 271 {
 272         const char *value;
 273
 274         if (git_config_get_value("pull.ff", &value))
 275                 return NULL;
 276
 277         switch (git_config_maybe_bool("pull.ff", value)) {
 278         case 0:
 279                 return "--no-ff";
 280         case 1:
 281                 return "--ff";
 282         }
 283
 284         if (!strcmp(value, "only"))
 285                 return "--ff-only";
 286
 287         die(_("Invalid value for pull.ff: %s"), value);
 288 }
 289
 290 /**
 291  * Returns the default configured value for --rebase. It first looks for the
 292  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 293  * branch, and if HEAD is detached or the configuration key does not exist,
 294  * looks for the value of "pull.rebase". If both configuration keys do not
 295  * exist, returns REBASE_FALSE.
 296  */
 297 static enum rebase_type config_get_rebase(void)
 298 {
 299         struct branch *curr_branch = branch_get("HEAD");
 300         const char *value;
 301
 302         if (curr_branch) {
 303                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 304
 305                 if (!git_config_get_value(key, &value)) {
 306                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 307                         free(key);
 308                         return ret;
 309                 }
 310
 311                 free(key);
 312         }
 313
 314         if (!git_config_get_value("pull.rebase", &value))
 315                 return parse_config_rebase("pull.rebase", value, 1);
 316
 317         return REBASE_FALSE;
 318 }
 319
 320 /**
 321  * Read config variables.
 322  */
 323 static int git_pull_config(const char *var, const char *value, void *cb)
 324 {
 325         if (!strcmp(var, "rebase.autostash")) {
 326                 config_autostash = git_config_bool(var, value);
 327                 return 0;
 328         }
 329         return git_default_config(var, value, cb);
 330 }
 331
 332 /**
 333  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 334  * into merge_heads.
 335  */
 336 static void get_merge_heads(struct oid_array *merge_heads)
 337 {
 338         const char *filename = git_path_fetch_head();
 339         FILE *fp;
 340         struct strbuf sb = STRBUF_INIT;
 341         struct object_id oid;
 342
 343         fp = xfopen(filename, "r");
 344         while (strbuf_getline_lf(&sb, fp) != EOF) {
 345                 if (get_oid_hex(sb.buf, &oid))
 346                         continue;  /* invalid line: does not start with SHA1 */
 347                 if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
 348                         continue;  /* ref is not-for-merge */
 349                 oid_array_append(merge_heads, &oid);
 350         }
 351         fclose(fp);
 352         strbuf_release(&sb);
 353 }
 354
 355 /**
 356  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 357  * retrieve the name of the remote if the repository only has one remote.
 358  */
 359 static int get_only_remote(struct remote *remote, void *cb_data)
 360 {
 361         const char **remote_name = cb_data;
 362
 363         if (*remote_name)
 364                 return -1;
 365
 366         *remote_name = remote->name;
 367         return 0;
 368 }
 369
 370 /**
 371  * Dies with the appropriate reason for why there are no merge candidates:
 372  *
 373  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 374  *    up not fetching anything. This is usually because the user provided a
 375  *    wildcard refspec which had no matches on the remote end.
 376  *
 377  * 2. We fetched from a non-default remote, but didn't specify a branch to
 378  *    merge. We can't use the configured one because it applies to the default
 379  *    remote, thus the user must specify the branches to merge.
 380  *
 381  * 3. We fetched from the branch's or repo's default remote, but:
 382  *
 383  *    a. We are not on a branch, so there will never be a configured branch to
 384  *       merge with.
 385  *
 386  *    b. We are on a branch, but there is no configured branch to merge with.
 387  *
 388  * 4. We fetched from the branch's or repo's default remote, but the configured
 389  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 390  *    part of the configured fetch refspec.)
 391  */
 392 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 393 {
 394         struct branch *curr_branch = branch_get("HEAD");
 395         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 396
 397         if (*refspecs) {
 398                 if (opt_rebase)
 399                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 400                 else
 401                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 402                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 403                                         "matches on the remote end."));
 404         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 405                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 406                         "a branch. Because this is not the default configured remote\n"
 407                         "for your current branch, you must specify a branch on the command line."),
 408                         repo);
 409         } else if (!curr_branch) {
 410                 fprintf_ln(stderr, _("You are not currently on a branch."));
 411                 if (opt_rebase)
 412                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 413                 else
 414                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 415                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 416                 fprintf(stderr, "\n");
 417                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 418                 fprintf(stderr, "\n");
 419         } else if (!curr_branch->merge_nr) {
 420                 const char *remote_name = NULL;
 421
 422                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 423                         remote_name = _("<remote>");
 424
 425                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 426                 if (opt_rebase)
 427                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 428                 else
 429                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 430                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 431                 fprintf(stderr, "\n");
 432                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 433                 fprintf(stderr, "\n");
 434                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 435                 fprintf(stderr, "\n");
 436                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 437                                 remote_name, _("<branch>"), curr_branch->name);
 438         } else
 439                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 440                         "from the remote, but no such ref was fetched."),
 441                         *curr_branch->merge_name);
 442         exit(1);
 443 }
 444
 445 /**
 446  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 447  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 448  * is not provided in argv, it is set to NULL.
 449  */
 450 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 451                 const char ***refspecs)
 452 {
 453         if (argc > 0) {
 454                 *repo = *argv++;
 455                 argc--;
 456         } else
 457                 *repo = NULL;
 458         *refspecs = argv;
 459 }
 460
 461 /**
 462  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 463  * repository and refspecs to fetch, or NULL if they are not provided.
 464  */
 465 static int run_fetch(const char *repo, const char **refspecs)
 466 {
 467         struct argv_array args = ARGV_ARRAY_INIT;
 468         int ret;
 469
 470         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 471
 472         /* Shared options */
 473         argv_push_verbosity(&args);
 474         if (opt_progress)
 475                 argv_array_push(&args, opt_progress);
 476
 477         /* Options passed to git-fetch */
 478         if (opt_all)
 479                 argv_array_push(&args, opt_all);
 480         if (opt_append)
 481                 argv_array_push(&args, opt_append);
 482         if (opt_upload_pack)
 483                 argv_array_push(&args, opt_upload_pack);
 484         argv_push_force(&args);
 485         if (opt_tags)
 486                 argv_array_push(&args, opt_tags);
 487         if (opt_prune)
 488                 argv_array_push(&args, opt_prune);
 489         if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
 490                 switch (recurse_submodules) {
 491                 case RECURSE_SUBMODULES_ON:
 492                         argv_array_push(&args, "--recurse-submodules=on");
 493                         break;
 494                 case RECURSE_SUBMODULES_OFF:
 495                         argv_array_push(&args, "--recurse-submodules=no");
 496                         break;
 497                 case RECURSE_SUBMODULES_ON_DEMAND:
 498                         argv_array_push(&args, "--recurse-submodules=on-demand");
 499                         break;
 500                 default:
 501                         BUG("submodule recursion option not understood");
 502                 }
 503         if (max_children)
 504                 argv_array_push(&args, max_children);
 505         if (opt_dry_run)
 506                 argv_array_push(&args, "--dry-run");
 507         if (opt_keep)
 508                 argv_array_push(&args, opt_keep);
 509         if (opt_depth)
 510                 argv_array_push(&args, opt_depth);
 511         if (opt_unshallow)
 512                 argv_array_push(&args, opt_unshallow);
 513         if (opt_update_shallow)
 514                 argv_array_push(&args, opt_update_shallow);
 515         if (opt_refmap)
 516                 argv_array_push(&args, opt_refmap);
 517
 518         if (repo) {
 519                 argv_array_push(&args, repo);
 520                 argv_array_pushv(&args, refspecs);
 521         } else if (*refspecs)
 522                 die("BUG: refspecs without repo?");
 523         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 524         argv_array_clear(&args);
 525         return ret;
 526 }
 527
 528 /**
 529  * "Pulls into void" by branching off merge_head.
 530  */
 531 static int pull_into_void(const struct object_id *merge_head,
 532                 const struct object_id *curr_head)
 533 {
 534         /*
 535          * Two-way merge: we treat the index as based on an empty tree,
 536          * and try to fast-forward to HEAD. This ensures we will not lose
 537          * index/worktree changes that the user already made on the unborn
 538          * branch.
 539          */
 540         if (checkout_fast_forward(&empty_tree_oid, merge_head, 0))
 541                 return 1;
 542
 543         if (update_ref("initial pull", "HEAD", merge_head->hash, curr_head->hash, 0, UPDATE_REFS_DIE_ON_ERR))
 544                 return 1;
 545
 546         return 0;
 547 }
 548
 549 static int rebase_submodules(void)
 550 {
 551         struct child_process cp = CHILD_PROCESS_INIT;
 552
 553         cp.git_cmd = 1;
 554         cp.no_stdin = 1;
 555         argv_array_pushl(&cp.args, "submodule", "update",
 556                                    "--recursive", "--rebase", NULL);
 557
 558         return run_command(&cp);
 559 }
 560
 561 static int update_submodules(void)
 562 {
 563         struct child_process cp = CHILD_PROCESS_INIT;
 564
 565         cp.git_cmd = 1;
 566         cp.no_stdin = 1;
 567         argv_array_pushl(&cp.args, "submodule", "update",
 568                                    "--recursive", "--checkout", NULL);
 569
 570         return run_command(&cp);
 571 }
 572
 573 /**
 574  * Runs git-merge, returning its exit status.
 575  */
 576 static int run_merge(void)
 577 {
 578         int ret;
 579         struct argv_array args = ARGV_ARRAY_INIT;
 580
 581         argv_array_pushl(&args, "merge", NULL);
 582
 583         /* Shared options */
 584         argv_push_verbosity(&args);
 585         if (opt_progress)
 586                 argv_array_push(&args, opt_progress);
 587
 588         /* Options passed to git-merge */
 589         if (opt_diffstat)
 590                 argv_array_push(&args, opt_diffstat);
 591         if (opt_log)
 592                 argv_array_push(&args, opt_log);
 593         if (opt_squash)
 594                 argv_array_push(&args, opt_squash);
 595         if (opt_commit)
 596                 argv_array_push(&args, opt_commit);
 597         if (opt_edit)
 598                 argv_array_push(&args, opt_edit);
 599         if (opt_ff)
 600                 argv_array_push(&args, opt_ff);
 601         if (opt_verify_signatures)
 602                 argv_array_push(&args, opt_verify_signatures);
 603         argv_array_pushv(&args, opt_strategies.argv);
 604         argv_array_pushv(&args, opt_strategy_opts.argv);
 605         if (opt_gpg_sign)
 606                 argv_array_push(&args, opt_gpg_sign);
 607         if (opt_allow_unrelated_histories > 0)
 608                 argv_array_push(&args, "--allow-unrelated-histories");
 609
 610         argv_array_push(&args, "FETCH_HEAD");
 611         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 612         argv_array_clear(&args);
 613         return ret;
 614 }
 615
 616 /**
 617  * Returns remote's upstream branch for the current branch. If remote is NULL,
 618  * the current branch's configured default remote is used. Returns NULL if
 619  * `remote` does not name a valid remote, HEAD does not point to a branch,
 620  * remote is not the branch's configured remote or the branch does not have any
 621  * configured upstream branch.
 622  */
 623 static const char *get_upstream_branch(const char *remote)
 624 {
 625         struct remote *rm;
 626         struct branch *curr_branch;
 627         const char *curr_branch_remote;
 628
 629         rm = remote_get(remote);
 630         if (!rm)
 631                 return NULL;
 632
 633         curr_branch = branch_get("HEAD");
 634         if (!curr_branch)
 635                 return NULL;
 636
 637         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 638         assert(curr_branch_remote);
 639
 640         if (strcmp(curr_branch_remote, rm->name))
 641                 return NULL;
 642
 643         return branch_get_upstream(curr_branch, NULL);
 644 }
 645
 646 /**
 647  * Derives the remote tracking branch from the remote and refspec.
 648  *
 649  * FIXME: The current implementation assumes the default mapping of
 650  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 651  */
 652 static const char *get_tracking_branch(const char *remote, const char *refspec)
 653 {
 654         struct refspec *spec;
 655         const char *spec_src;
 656         const char *merge_branch;
 657
 658         spec = parse_fetch_refspec(1, &refspec);
 659         spec_src = spec->src;
 660         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 661                 spec_src = "HEAD";
 662         else if (skip_prefix(spec_src, "heads/", &spec_src))
 663                 ;
 664         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 665                 ;
 666         else if (starts_with(spec_src, "refs/") ||
 667                 starts_with(spec_src, "tags/") ||
 668                 starts_with(spec_src, "remotes/"))
 669                 spec_src = "";
 670
 671         if (*spec_src) {
 672                 if (!strcmp(remote, "."))
 673                         merge_branch = mkpath("refs/heads/%s", spec_src);
 674                 else
 675                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 676         } else
 677                 merge_branch = NULL;
 678
 679         free_refspec(1, spec);
 680         return merge_branch;
 681 }
 682
 683 /**
 684  * Given the repo and refspecs, sets fork_point to the point at which the
 685  * current branch forked from its remote tracking branch. Returns 0 on success,
 686  * -1 on failure.
 687  */
 688 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 689                 const char *refspec)
 690 {
 691         int ret;
 692         struct branch *curr_branch;
 693         const char *remote_branch;
 694         struct child_process cp = CHILD_PROCESS_INIT;
 695         struct strbuf sb = STRBUF_INIT;
 696
 697         curr_branch = branch_get("HEAD");
 698         if (!curr_branch)
 699                 return -1;
 700
 701         if (refspec)
 702                 remote_branch = get_tracking_branch(repo, refspec);
 703         else
 704                 remote_branch = get_upstream_branch(repo);
 705
 706         if (!remote_branch)
 707                 return -1;
 708
 709         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 710                         remote_branch, curr_branch->name, NULL);
 711         cp.no_stdin = 1;
 712         cp.no_stderr = 1;
 713         cp.git_cmd = 1;
 714
 715         ret = capture_command(&cp, &sb, GIT_SHA1_HEXSZ);
 716         if (ret)
 717                 goto cleanup;
 718
 719         ret = get_oid_hex(sb.buf, fork_point);
 720         if (ret)
 721                 goto cleanup;
 722
 723 cleanup:
 724         strbuf_release(&sb);
 725         return ret ? -1 : 0;
 726 }
 727
 728 /**
 729  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 730  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 731  */
 732 static int get_octopus_merge_base(struct object_id *merge_base,
 733                 const struct object_id *curr_head,
 734                 const struct object_id *merge_head,
 735                 const struct object_id *fork_point)
 736 {
 737         struct commit_list *revs = NULL, *result;
 738
 739         commit_list_insert(lookup_commit_reference(curr_head), &revs);
 740         commit_list_insert(lookup_commit_reference(merge_head), &revs);
 741         if (!is_null_oid(fork_point))
 742                 commit_list_insert(lookup_commit_reference(fork_point), &revs);
 743
 744         result = reduce_heads(get_octopus_merge_bases(revs));
 745         free_commit_list(revs);
 746         if (!result)
 747                 return 1;
 748
 749         oidcpy(merge_base, &result->item->object.oid);
 750         return 0;
 751 }
 752
 753 /**
 754  * Given the current HEAD SHA1, the merge head returned from git-fetch and the
 755  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 756  * appropriate arguments and returns its exit status.
 757  */
 758 static int run_rebase(const struct object_id *curr_head,
 759                 const struct object_id *merge_head,
 760                 const struct object_id *fork_point)
 761 {
 762         int ret;
 763         struct object_id oct_merge_base;
 764         struct argv_array args = ARGV_ARRAY_INIT;
 765
 766         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 767                 if (!is_null_oid(fork_point) && !oidcmp(&oct_merge_base, fork_point))
 768                         fork_point = NULL;
 769
 770         argv_array_push(&args, "rebase");
 771
 772         /* Shared options */
 773         argv_push_verbosity(&args);
 774
 775         /* Options passed to git-rebase */
 776         if (opt_rebase == REBASE_PRESERVE)
 777                 argv_array_push(&args, "--preserve-merges");
 778         else if (opt_rebase == REBASE_INTERACTIVE)
 779                 argv_array_push(&args, "--interactive");
 780         if (opt_diffstat)
 781                 argv_array_push(&args, opt_diffstat);
 782         argv_array_pushv(&args, opt_strategies.argv);
 783         argv_array_pushv(&args, opt_strategy_opts.argv);
 784         if (opt_gpg_sign)
 785                 argv_array_push(&args, opt_gpg_sign);
 786         if (opt_autostash == 0)
 787                 argv_array_push(&args, "--no-autostash");
 788         else if (opt_autostash == 1)
 789                 argv_array_push(&args, "--autostash");
 790         if (opt_verify_signatures &&
 791             !strcmp(opt_verify_signatures, "--verify-signatures"))
 792                 warning(_("ignoring --verify-signatures for rebase"));
 793
 794         argv_array_push(&args, "--onto");
 795         argv_array_push(&args, oid_to_hex(merge_head));
 796
 797         if (fork_point && !is_null_oid(fork_point))
 798                 argv_array_push(&args, oid_to_hex(fork_point));
 799         else
 800                 argv_array_push(&args, oid_to_hex(merge_head));
 801
 802         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 803         argv_array_clear(&args);
 804         return ret;
 805 }
 806
 807 int cmd_pull(int argc, const char **argv, const char *prefix)
 808 {
 809         const char *repo, **refspecs;
 810         struct oid_array merge_heads = OID_ARRAY_INIT;
 811         struct object_id orig_head, curr_head;
 812         struct object_id rebase_fork_point;
 813         int autostash;
 814
 815         if (!getenv("GIT_REFLOG_ACTION"))
 816                 set_reflog_message(argc, argv);
 817
 818         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 819
 820         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 821
 822         if (!opt_ff)
 823                 opt_ff = xstrdup_or_null(config_get_ff());
 824
 825         if (opt_rebase < 0)
 826                 opt_rebase = config_get_rebase();
 827
 828         git_config(git_pull_config, NULL);
 829
 830         if (read_cache_unmerged())
 831                 die_resolve_conflict("pull");
 832
 833         if (file_exists(git_path_merge_head()))
 834                 die_conclude_merge();
 835
 836         if (get_oid("HEAD", &orig_head))
 837                 oidclr(&orig_head);
 838
 839         if (!opt_rebase && opt_autostash != -1)
 840                 die(_("--[no-]autostash option is only valid with --rebase."));
 841
 842         autostash = config_autostash;
 843         if (opt_rebase) {
 844                 if (opt_autostash != -1)
 845                         autostash = opt_autostash;
 846
 847                 if (is_null_oid(&orig_head) && !is_cache_unborn())
 848                         die(_("Updating an unborn branch with changes added to the index."));
 849
 850                 if (!autostash)
 851                         require_clean_work_tree(N_("pull with rebase"),
 852                                 _("please commit or stash them."), 1, 0);
 853
 854                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
 855                         oidclr(&rebase_fork_point);
 856         }
 857
 858         if (run_fetch(repo, refspecs))
 859                 return 1;
 860
 861         if (opt_dry_run)
 862                 return 0;
 863
 864         if (get_oid("HEAD", &curr_head))
 865                 oidclr(&curr_head);
 866
 867         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
 868                         oidcmp(&orig_head, &curr_head)) {
 869                 /*
 870                  * The fetch involved updating the current branch.
 871                  *
 872                  * The working tree and the index file are still based on
 873                  * orig_head commit, but we are merging into curr_head.
 874                  * Update the working tree to match curr_head.
 875                  */
 876
 877                 warning(_("fetch updated the current branch head.\n"
 878                         "fast-forwarding your working tree from\n"
 879                         "commit %s."), oid_to_hex(&orig_head));
 880
 881                 if (checkout_fast_forward(&orig_head, &curr_head, 0))
 882                         die(_("Cannot fast-forward your working tree.\n"
 883                                 "After making sure that you saved anything precious from\n"
 884                                 "$ git diff %s\n"
 885                                 "output, run\n"
 886                                 "$ git reset --hard\n"
 887                                 "to recover."), oid_to_hex(&orig_head));
 888         }
 889
 890         get_merge_heads(&merge_heads);
 891
 892         if (!merge_heads.nr)
 893                 die_no_merge_candidates(repo, refspecs);
 894
 895         if (is_null_oid(&orig_head)) {
 896                 if (merge_heads.nr > 1)
 897                         die(_("Cannot merge multiple branches into empty head."));
 898                 return pull_into_void(merge_heads.oid, &curr_head);
 899         }
 900         if (opt_rebase && merge_heads.nr > 1)
 901                 die(_("Cannot rebase onto multiple branches."));
 902
 903         if (opt_rebase) {
 904                 int ret = 0;
 905                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
 906                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
 907                     submodule_touches_in_range(&rebase_fork_point, &curr_head))
 908                         die(_("cannot rebase with locally recorded submodule modifications"));
 909                 if (!autostash) {
 910                         struct commit_list *list = NULL;
 911                         struct commit *merge_head, *head;
 912
 913                         head = lookup_commit_reference(&orig_head);
 914                         commit_list_insert(head, &list);
 915                         merge_head = lookup_commit_reference(&merge_heads.oid[0]);
 916                         if (is_descendant_of(merge_head, list)) {
 917                                 /* we can fast-forward this without invoking rebase */
 918                                 opt_ff = "--ff-only";
 919                                 ret = run_merge();
 920                         }
 921                 }
 922                 ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 923
 924                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 925                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 926                         ret = rebase_submodules();
 927
 928                 return ret;
 929         } else {
 930                 int ret = run_merge();
 931                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 932                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 933                         ret = update_submodules();
 934                 return ret;
 935         }
 936 }